The dual demographic changes in massive rural-to-urban labour migration and population ageing have significantly impacted the lives of older adults, who have either been left behind in rural regions or migrated to urban areas. While many extant studies on migration and wellbeing of older adults have focused on either migrating or left-behind older adults, a very limited number of studies have directly compared these two groups. Utilising data from the China Longitudinal Ageing Social Survey, this study examines the impacts of different migration patterns (i.e. migrating older adults, left-behind older adults and non-migrating older adults) on the social networks and mental health of older adults in rural China. Structural equation modelling results showed that older adults who have been left behind reported weaker family ties and poorer mental health than the other older adults. Moreover, weakened family ties increased older adults’ risk of developing mental health problems. Older migrants reported the lowest level of depressive symptoms among the three groups of older adults. However, migration may be associated with poorer mental health among the older migrants due to the shrinking/weakening of family/friendship ties.